"Magnetic excitations in spin-liquids: from classical to quantum"

Mott insulators are of central importance in condensed matter physics because they often host exotic magnetic ground-states and excitations. This is particularly true for spin-liquids, correlated yet fluctuating states of magnetic matter stabilized by e.g. low-dimensionality, geometrical frustration, spin-orbit coupling and/or disorder. As for conventional liquids, both classical and quantum spin-liquids exist and a central question is to determine the nature of the quasiparticles governing their dynamics. I will present inelastic neutron scattering investigations from a selection of single-crystalline magnetic materials [1,2,3] and address how to distinguish quantum from classical spin-liquids from their dynamical responses.